The panel of judges included head brewer at Fuller's John Keeling, last year's winner Chris Connor and guest judge and beer writer Des de Moor.
The pub impressed the judges by excelling in every area of quality control from cellar to glass.
Rennie, manager of the Crystal Palace, said she was delighted to win the award and added: "This is the third year we have been in contention for this award and I am so happy the hard work has paid off.
"My whole team works tirelessly and are dedicated to serving the best possible pints."
Judging
The judging process involves inspections of cellar hygiene and dispense equipment and quality checks completed by the Fuller's Beer Quality Team.
The award recognises continuously outstanding cellar quality in Fuller's pubs, and managers and tenants need to achieve a score of 96% over four visits from the Fuller's Beer Quality Team across the year to get into the final of the award.
Fuller's
John Keeling, Fuller's brewing director, said: "This is an incredible accolade for Kim and her team.
"They have done a fantastic job looking after and promoting our beers, always striving for that perfect pint."
He added it was a pleasure giving the award to people who understand and know their cellar and beer and those who are as passionate about them as he is.